Apparatus for extracting mandrels from cavitied plastic structures



!!Illa/ll!!!)II!I!III!!!llllllllflvIIIIIIIIIIII II IIII 4 Sheefs-Sheet 1 Dec. 25, 1951 GQNDA APPARATUS FOR EXTRACTING MANDRELS FROM CAVITIED PLASTIC STRUCTURES Filed July 10, 1948 INVENTOR. D ESIREI GoNoA.

ATTORNEY5.

Dec. 25, 1951 D. GONDA APPARATUS FOR EXTRACTING MANDRELS FROM CAVITIED PLASTIC STRUCTURES 4 Sheets-Sheet 2 Filed July 10, 1948 .3 a 00 R H 1' A m D W M MN 0 V o W W6 A E m. 7 1 a D Y 6 imd O0 Dec. 25 1951 D. GONDA 2,580,223

APPARATUS FOR EXTRACTING MANDRELS FROM CAVITIED PLASTIC STRUCTURES 4 Sheets-Sheet Filed July 10, 1948 jig-ya 15 INVENTOR.

DESIRE GONDA.

BY A

ATTORNEYS.

Dec. 25, 1951 o. GONDA 2 2,580,223

' APPARATUS FOR EXTRACTING MANDRELS FROM CAVITIED PLASTIC STRUCTURES Filed July 10, 1948 4 Sheets-Sheet 4 IN V EN TOR.

DESIRE GONDA. BY

ATTORNEYS.

Patented Dec. 25, 1951 22,580.223 "APPARA U from 'IEXTRACTINGMANDRELS FROM'CAVITIED PLASTIC STRUCTURES Desire t'Gon'da, Sittihgbourne, England, assign'or to-Holopastiimited, Kent, England, ,aiBr-itish Application'July' 10, IMSQSeriaI NO. 3820 38 I 2'. Claims. '1

This invention relates to methods/and appa- "ratus for removing mandrels and I the like from *the I cavities --6f pl'asti'c structures, such for exahipleas from therme se jlaminated plastic structural units which have been formed "under heat andpressure with s-u h-ma'ndrIS inpIace-therein for supportin'g theridav'ity walls during the press *in'goperatidn.

-'1he invention w'ill be'ilisclosed' as used in the manufacture 'o'f nteg a laminated thermo-set -pla'stic striictur fthe type, T for exampl disclosed in Myra-pendin application Serial No. 5795429. filed' 1 'ebri1ary-2 3,' 1945 (riow Patent No. 254453290, g ranted dulyfiil, 1948) which application"was-' -a division of rny "application Serial "No. 424,09Ojfiled' Dec'ember ZZ, 1 9l1,'now abandoned. Such structural have spaced-apart panellike portionsv/hich a're interconnected by spaced Webs wi th 1 generally parallel channel-like openended cavities defined' -by sai'd p'o'rtions andwe'bs. According to'the example of the invention here disclosed, the manufacture of such structural units involves subjecting the-plastic assembly to elevated temperature for thermo-setting the'plastic material whi-l'e -applying hi'ghpressure thereto in directions tending to reduce the cross-sectional dimensio'iis fif the cav ities, but each cav-ity being "meanwhile filled with t'wo or inore l cornplementary longitudinal tapered mandrels 'designed and'arra'ngedso that their larger ends are adapted to he gripped for"with'drawa1 at oppo- "site-ends of the cavity aft'er'the completion of "the temperature and "pressure treatment.

lhe curing of s-uch" structural units at elevated temperatureis preferably carried out under pres- "sure in the neighborhood of 1500 lbs.- per square inch, and accordingly if the cavities areof substantial size "or length, the'mandrels 'will be so securely gripped therein, that the problem of dislOdg-ing and extracting= sa'mepresents seriousdif- 'ficulties which, so far as "I am aware, have not "been-solved prior'to my inventio'n hereof, and "have no comparable =counterpartfin the plastics industrymriother arts. Forexample; ifa pair dftapered'mandrelsareto berem'oved from such -"a 'cavity which'is "about '8' long and having a "cross-section, for example, of by about 2", it will be found that a force in'the neighborhood of 100 tonso'r more mayhave to be'applied to start'th'e extracting movement of'each individual :mandrel. The laminated structural unit as v:"formed in the 'press will ordinarily have rough Efeather'ed edges of the laminae around adj'acent theieprotrudingcmarrdreliends,sshthat no secure fstop :meanscan herapplied; around Ladjacent the 'moiith or the c'avit'y' to hold the unit *securely against movement while a force of "such magnitude isappli'ed to 'extra'ct'the'mandrel. Further more; if anyattempt'lis 'madeto clamp the structural un it withisufficient pressure against itswall surfaces "toho'ld 'it in' place during theappiication'of 'any extracting 'fo'rceof such magnitude to the Y mandrel, "then the' clampin'g' pressure will only'ca'usei the mandrelt'obe all the more securely clamped in the cavity, inasmuch as'the cavity "wallsw'ill 'be:2rsufiicientlyflexib1e to yield against 'any' such"l'leavyrpressure'as' would be required in proceeding in that-way.

According 'to zthe presnet invention the'above explained Fdifficult-iesrare overcome-by a method which involves as ioneiofr its features the simultaneousiapplication'fofzpowerfuland substantially equal and oppositely directed extracting forces to the grip'portionsrotmandrels at opposite 'cavity ends respectively, rand *by such forces with- "drawing aan eqi1al number of mandrels each "directionsimultaneously. By proceeding in *this way, it is unnecessary tcr apply any firm stop means fagainst.the'structuralsunit to prevent its movement during the extral'ction proc'e'ss, andin'eitherris it necessary "itO i appl'y fariy substantial pressure to the unit rato prevent its tmovement, "although a small amountn "clamping pressure "may be .ini- -1't-ial1y iapplieileto. prevent-any undesired movement which might otherwise result from the slight dif- :"rere'n'ces 'between the two oppositely directed extraction forces, "or the difierence's in 'friction cagainst the :hppositely extracted 'inandrels :re-

' spectively.

Various further'i-and' more specific features, 'objeots and advantageso'f the invention will clearly 'la'r'ipeal' from the dtaileddescription given' below, taken in connection with the accompanying drawingswhich form a part of "this specification-and illustrate byway of exampleapreferred embodimentmf apparatus ;for carrying out the invention.

In the drawings: Figure .1 J "is a 's'ide I'l'vational :viewlof ione-Tform .df'lhydiaulic extraction. apparatus "which may i be used.in,pra'cticing.the invention;

Tigazisaviewshowing one of theends of the apparatus-ofFig; 1;

;Fig. :3 is a sectional'view takensubstantially alongrline d an-of Fig.4

--=Fig. liillustrates-inl'plan view aicavitied i'lamiinatedsstructural-aniit-rwith mandrels in the cavii'ties thereof lami sshowing the appearance of the pecass'embly it "comes from the pressing l'operation and also showing the manner in which the mandrels are gripped for extraction;

Fig. 5 is an edge view partly in section (along the line 5-5 of Fig. 4) of the assembly of Fig. 4;

Fig. 6 is a plan View showing a pair of complementary tapered mandrels in the relationship which they bear to each other when within a cavity of the structural unit of Fig. 4;

Fig. '7 is a detailed perspective View showing one simpe form of apparatus for supportin and hoding the s ructural unit during t e mandrel extraction operation by the apparatus of Fi 1;

Fig. 8 is a bottom-side-up perspective view of the camping frame shown in Fig. '7;

Fig. 9 is a fragmentary corner view showing such clamping frame as applied to the structural unit and mandrel assembly; and

Figs. 10 and 11 are vertical sectional views partly broken away, showing the portion of the tural cavitied lamina ed plastic units such as disc osed in my above-mentioned co-pending application is shown at [5 with'a pair of longitudinally tapered mandrels as at l6, l1 filling each cavity. These mandrels are preferably so shaped as shown in Fig. 6 that the abuttin si e surfaces thereof respectively will be gradually tapered from one end to the other. Two or more of such comp ementary tapered mandrels may be used coniointly having a cross-section of dirrensions such as to completely fill one of the cavities in th structural unit. The larger end of each mandrel preferably is such as to p otrude outside the end of the mouth of he cav ity to form a grip portion as shown at is in Figs. 5 and 6, although it will be apprecia ed that various other forms of grip portions might be prov ded. As shown, these grip portions may comprise metal pl tes as at I 8', I8, riveted, as indicated in Fig. 5, to the upper and lower surfaces of the end of the mandrel.

As indicated in Figs. 4 and 5, the mandrel grip portions may be gripped in jaw structures 20, comprising a rigid. upper jaw portion 2|, rne of these jaw portions being provided on each end of the extracting apparatus as shown in Fig. 1, the portions 2! extending into the large heavy head blocks 22. These blocks are formed with cavities as at 23 within which head portions 24 on the memb rs 2| may he slid into place sideways, connectin the jaws to the head blocks 22. On its lo -er side, each of the jaw members 2|. has bolted thereto a lower complementary jaw portion 25. As indicated in Fig. 4, the jaws are wide enough so that the assembly of the mandrels in the structural unit may be slid in side-- ways of the jaws, as shown in Fig. 4, into a position such that the jaws embrace all of the mandrel grip portions at one time.

However, as further shown in Fig. 4, the mandrels are so positioned or are made of such length, that they do not all extend to equal distances from the cavity ends. That is, for example, the grip portions [8a on the mandrels which are located in the two cavities at the edges of the unt [5, are preferably positioned closer to the unit l5 than are the grip portions on the other mandrels, so that as the jaws are moved apart in cpposite directions (as indicated by the arrows on Fig. 4), the mandrels in these two outer cavities will be gripped first, and the extraction thereof started 4 before the jaws start to extract other mandrels. In other words, with the arrangement of the grip portions of the mandrel as shown, the initial mov-ment of the jaws 20 will start the extraction of all four of the mandrels in the outer two cavities simultaneously. Thus the extracting forces at the opposite ends of these two cavities may be even y balanced wih respect to the mid portion of the structural unit, and two equal and opposite forces at opposite cavity ends on the mandrels, will counteract each other without causing any such force to be applied to the structural unit as might tend to move it sideways or to turn it to any angle to the position shown in Fig. 4. As further shown in Fig. 4, very shortly after the mandrel grip portions l8a have been en-aged by the jaws 20 (or even practically concurrently therewith, if desired) the four mandrel grip portions |8b will be engaged by the jaws to start the extraction of four more of the mandrels which are a so symmetrically ositioned with respect to the middle portion of the structural unit. Next rip portions I of eight other mandrels will be engaged "nd the extraction of such mandres will be star ed. Similarly it will be apparent that the startng of the extraction of the remaining groups of the mandrels may be accomp i had in succesuon, the mandrelsof each group wh'ch are started concurrently preferably being symmetrical'y arranged with respect to the cent'r of the structu a1 unit to avoid any non-symmetrical or turn ng forces on the unit which might cause cracking or greater friction against extraction of the mandrels. It will be apparent that the starting of the extraction of the mandrels successively in groups makes it possible to use an extracting force which is much less powerful than would be the case if all of the mandrels were disodged concurrently. The starting of the extraction of eight of the mandrels concurrently (four in each direction) as in the case of the mandrels 28c above-mentioned, requires for a structural unit of the above stated dimensions, powerful equal and opposite forces in the neighborhood of 500 tons.

' Thus the starting of the extraction of the mandrels in groups successively avoids the necessity of apparatus of practically prohibitive dimensions, cost and power, which would otherwise be necesary.

Referring now more particularly to Fig. l, the hydraulic apparatus there shown may comprise for example four powerful hydraulic cylinders of suitable known construction as at 30, having plungers as at 3| positioned to initially protrude and push against the head blocks 22 for starting the movement thereof to effect the initial extraction movement of the mandrels. These plungers and accompanying cylinders may be so designed as to apply the above-mentioned initial force of 500 tons against the head blocks respectively in opposite direction and with a stroke of 2" for example, which is sufficient to start the extraction of all of the mandrels. These plungers may surround smaller plungers as at 32 which start to protrude and push against the head blocks 22 after completion of the stroke of the plungers 3 I. These latter plungers may be designed in conjunction with cylinder structure 30 to operate with a stroke of 6", for example, and thereby to apply equal and opposite forces in the neighborhood of 250 tons further to extract the mandrels. The specific manner in which'the cylinders 30 and the concentric plungers therein may be constructed and designed to operate as above explained, is well known in hydraulic appasausa es matus andracccrdinglyneed: not'beyhere described :5 in further detail.

It-will be noted' that the' hydraulic cylindersand the plungers therein are :positioned'symmetideally-above and' belowwith respectitoithe manwingwany possibility of turning or twistingthe man" drels which would result in-injury to the structural unit .or .increase the frictional resistance against the mandrels. Each of the head blocks, as shown in Figs; 1 and 2, may be supported on Wheels orttrucks-as at 33 running on 'trac'ks a'i i.

.Upon completion-of the .B in'ch strokes of the -plungers 132, further extraction of the rnandrels -.is effected by the action :of long-stroke plungers i35-.38 inclusive,theseplungers at the outer ends 'beingirigidlyeffixed.to .thezhe'ad blocks 2 2 and:

serving to hold the latter in upright position as they are shoved along the tracks 35. The inner ends of the plungers 3538 are received in hydraulic cylinders 35a38a, inclusive, designed to impart to the plungers a stroke for example of about 9 feet, and to provide equal and opposite forces each totaling from 20 to l tons. It will be noted, as best indicated in Fig. 3, that the plungers 35 and 3B are positioned respectively at equal distances above and below the mandrel assembly to be extracted and at equal distances to each side of the hydraulic cylinders 36 for thrusting out the head block 22 at the right hand end of Fig. 1. The plungers 31 and 33 are positioned similarly to operate the head block 22 at the left hand end of Fig. 1.

As indicated in Fig. 3, the upper and lower hydraulic cylinders may be mounted upon upper and lower rigid frame structures til, dl between which the assembly of apparatus of Fig. 7 is mounted for receiving the structural unit and mandrel assembly to be acted upon, such assembly being slidable into place from the right side of the apparatus as viewed in Fig. 3, suitable table means with rollers for this purpose being indicated at 42. The structure as shown in Fig. 7 comprises three table portions as at 43, M, 55, surfaced, for example, with hard rubber as at 46, these table portions being suitably mounted in stationary position upon the frame structure 4|. structures as at 41, 48 are positined along within the gaps between the table areas 43-45, these bars serving to carry rollers as at 49, upon which the assembly l5 may be rolled into place as shown in Fig. 10. The slotted bars 57, 48 are supported at their ends by hydraulic cylinder and plunger devices as at 50, so that after the assembly i5 i in the position shown in Fig. 10, the slotted bars and rollers may be lowered by actuation of the hydraulic devices to the position indicated in Fig. 11, where the rollers 39 are shown depressed out of contact with the assembly i5, so that the latter will now rest upon the hard rubber surfaced table portions d3 fil5. Spring means as at 5! may be provided to insure that the roller assemblies will be pulled down into depressed position upon release of the pressure in the hydraulic devices 50.

A frame structure 52 is suspended above the table portions l3t5 by a plurality of hydraulic cylinder and plunger devices as indicated at 53. This frame structure may comprise a metal part 54 shaped to conform substantially to the perimeter of the assembly I 5 to be acted upon and having, if desired, a central cross piece 54a. The

1 under side 0f 'lthis *frame may 1 besurtfaced 'with hard rubber as at55:for engaging" thel-assembly 115 when the-hydraulic devices 53:-are actuated to lower the frame. "Metal corner iblocksas at= 56 5 are provided on the under surface of the frame in 'positions -to engage, when the'frame'is lowered, the endedges of the assembly 1 15, thereby to olfer some ':resistance against :endwise displacement :of such zassembly. It will be understood that :10 when theassembly i5 is slid into place, :the hydraulicallyoperated headblocks 2 2 will be in'rel-tracted positionfiso that the mandrel assemblies :may beslid sidewise'into the clampsZB, whereupon-after-the:assembly1:5 is in place,'-as indi- 'cated inFig. 10,-thehydraulic devices 50 and 53 are actuated' to support the assemblyinthe position shown .inFig. 11 and retain 'it'in such position-witha'certainidegree of firmness.

As shown in Figs.- 4, 10 and 11, the'two outersi'de edge-cavities cf the assembly [-5 may be filled with strips of wood as at 51, which do not have to be extracted if it is desired to use such wood in nailing or otherwise securing the structural unit in place during use. If it is desired to have these outer edge cavities open in the finished unit,

they may be filled by metal members, the removal of which presents no problem since the sides of these cavities are open. In either event, as will be apparent from Figs. 7, 10 and 11, the

frame 52 is so constructed and the hydraulic devices 53 are so positioned that the pressure applied in holding the assembly l5 in position is largely against the side edges of the assembly 15 where the inserts 5'! occur. Thus the application of pressure against the parts of the assembly where the mandrels occur, is substantially avoided, so that any added resistance against eX- traction of the mandrels is obviated.

After the actuation of the plungers 3|, 32,

35-38 to extract the mandrels, it will be apparent that the hydraulic devices 53 may be actuated to elevate the frame 52, whereupon the hydraulic devices may be actuated to elevate the rollers 49 and the assembly I5 may then be rolled out of the apparatus.

While the invention has been described in detail with respect to a particular preferred example, it will be understood by those skilled in the art after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention, and it is intended therefore in the appended claims to cover such changes and modifications.

What is claimed and desired to be secured by Letters. Patent is:

1. In apparatus for extracting mandrels from the opposite ends respectively of a plurality of parallel cavities in a plastic structural unit which has been treated under pressure with the mandrels therein, the combination comprising means for supporting and retaining the structural unit in generally horizontal position, power operated clamping means for applying pressure along the two side edges of the structural unit to press same against said supporting means to restrain movement of the unit, jaw means for engaging said mandrels at opposite ends of the structural unit,

means constructed and arranged to support said jaw means respectively for linear movement in opposite directions from said cavity ends, and fluid pressure operated plunger and cylinder means both above and below said frame means and constructed and arranged simultaneously to Slotted bar .3.)

thrust said jaw means in said opposite directions with substantially equal forces.

2. In apparatus for extracting mandrels from the opposite ends respectively of a plurality of substantially parallel cavities in a thermo-set plastic structural unit which has been treated under heat and pressure with the mandrels therein, the combination comprising table-like means for supporting and retaining the structural unit in generally horizontal position, a retaining frame shaped perimetrically to engage the upper surface of the panel, said frame including at its corners parts adapted to engage, when the frame is lowered into contact with the panel, the end edges of such panel adjacent the corners thereof to restrain same against endwise movement, power operated means for effecting the raising and lowering of said frame, jawmeans for engaging such mandrels at opposite ends of the structural unit, means constructed and arranged 8 to support said jaw means respectively for linear movement in opposite directions from said cavity ends, and fluid pressure operated plunger and cylinder means constructed and arranged simultaneously to thrust said jaw means in said opposite directions.

DESIRE GONDA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 15 1,394,558 Klug Oct. 25, 1921 1,673,603 Stoney June 12, 1928 2,029,048 Atwood Jan. 28, 1936 2,366,976 Martindell Jan. 9, 1945 2,433,546 Cornelius Dec. 30, 1947 go 2,445,290 Gonda July 13, 1948 

